This c5 envelope template is formatted for immediate printing and rapid home assembly. Engineered to print accurately on standard A4 paper, this template eliminates the need for emergency envelope purchases.

Key Features:

Exact Standard Dimensions: Folds perfectly into standard mailing sizes.
Clear Cut & Fold Lines: Unambiguous solid lines for cutting and dashed lines for folding.
Print Ready: Optimized for standard A4 paper trays.

Dimensions and Standards

Size: 162 x 229 mm
Usage: An international ISO standard envelope size.
Fit: Specifically dimensioned to hold an A4 sheet folded in half, or an unfolded sheet of A5 paper.

Rapid Assembly Instructions

Print: Print on A4 paper. Scale must be set to “Actual Size” or 100%.
Cut: Use a precision paper trimmer or sharp scissors to cut along the solid outer perimeter.
Score: For clean folds, lightly score along the dotted fold lines using a bone folder or the dull edge of a butter knife.
Fold: Fold the two side flaps inward, followed by folding the bottom flap upward.
Adhere: Apply a thin layer of glue stick or double-sided tape to the outer edges of the side flaps. Press the bottom flap firmly into place.

Tip: For postal durability and opacity, printing on heavier stock (such as 28lb or 32lb paper) is strongly advised.

By the Numbers

Finished envelope size: 162 × 229 mm (6.4 × 9 in)
Built for: A4 sheets folded in half, or A5 sheets flat

Who This Is For

Anyone mailing A4 documents without folding them into quarters – C5 is the ISO standard size built to take an A4 sheet folded once, or an A5 sheet unfolded.

Frequently Asked Questions

What paper weight works best for a DIY envelope?

Standard 20lb copy paper folds cleanly but can feel flimsy for a formal mailing. For invitations or anything mailed to guests, 24-32lb paper (or light cardstock) holds a crisper fold and feels closer to a purchased envelope.

What does the Interactive Generator let me change that this static PDF doesn’t?

This page is a fixed, pre-configured version. The generator behind it lets you adjust the base paper size the envelope is cut from, which changes how much trim waste is left over after cutting.

Also Available

C5 is the ISO standard for A4/A5 documents. Mailing a standard US business letter instead? See #10. Sending a 5x7 card or invitation? See A7.

One More Thing

C5 is part of the ISO 216 envelope series, which is designed so an A4 sheet folded exactly in half becomes A5 – the same size as this envelope’s opening, with no trimming needed.

Storage and Care

After cutting and folding, press the folded flaps under a stack of books overnight before adhering them – home-cut and folded paper doesn’t hold a crease as crisply as a machine-made envelope straight out of the box, and a flat, well-set fold looks noticeably more finished once addressed and posted.

Using This Digitally

If you’re printing at a copy shop rather than at home, most will accept this PDF directly – confirm they print at “Actual Size” or 100% scale rather than their default “fit to page” setting, since commercial printers and copiers default to auto-scaling just as often as home inkjets do. Bring a ruler to check the first proof before running a full batch.

A Note on Color

All line and guide colors on this site are chosen to photograph and photocopy predictably – if you plan to scan or copy a finished page rather than keep the original, a quick test copy is worth running before you commit a whole project to one setting, since screen colors and printed colors don’t always match exactly.

Printable C5 Envelope